How is postoperative respiratory failure defined? What are the two main types of acute respiratory failure?

How is postoperative respiratory failure defined? What are the two main types of acute respiratory failure?

Postoperative respiratory failure is defined as the need for continued mechanical ventilation beyond 48 hours after surgery, or the need for reintubation and mechanical ventilation after extubation.

There are two categories of respiratory failure: hypox-emic or type I (usually with a low or normal PCO₂) and hypercapnic or type II. Hypoxemia is discussed in detail in the next section. Hypercapnia is caused by either ineffective minute ventilation or, much less commonly, excessive carbon dioxide (CO₂) production (e.g., malignant hyperthermia or overzealous carbohydrate feeding). Ineffective ventilation may result from a low respiratory rate (e.g., opioid effect), a low tidal volume (e.g., neuromuscular weakness or splinting from pain), or an increase in physiologic dead-space (e.g., COPD, pulmonary embolus, acute respiratory distress syndrome, or shock).